Indistinguishability of quantum states and rotation counting

Abstract

We propose a quantum system in which the winding number of rotations of a particle around a ring can be monitored and emerges as a physical observable. We explicitly analyze the situation when, as a result of the monitoring of the winding number, the period of the orbital motion of the particle is extended to $n>1$ full rotations, which leads to changes in the energy spectrum and in all observable properties. In particular, we show that in this case, the usual magnetic flux period $\Phi_0=h/q$ of the Aharonov-Bohm effect is reduced to $\Phi_0/n$.